Move more parts of stack trace formatting to runtime.

test/mjsunit/stack-traces-custom.js

Index: test/mjsunit/stack-traces-custom.js
diff --git a/test/mjsunit/stack-traces-custom.js b/test/mjsunit/stack-traces-custom.js
new file mode 100644
index 0000000000000000000000000000000000000000..fbf650ddbfd35f874ab447927cb64e0d9ca8bba3
--- /dev/null
+++ b/test/mjsunit/stack-traces-custom.js
@@ -0,0 +1,20 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+var o = { f: function() { throw new Error(); } };
+o.g1 = function() { o.f() }
+o.g2 = o.g1;
+o.h = function() { o.g1() }
+
+Error.prepareStackTrace = function(e, frames) { return frames; }
+
+try {
+  o.h();
+} catch (e) {
+  var frames = e.stack;
+  assertEquals("f", frames[0].getMethodName());
+  assertEquals(null, frames[1].getMethodName());
+  assertEquals("h", frames[2].getMethodName());
+  assertEquals(null, frames[3].getMethodName());
+}